Symmetry-Broken Chern Insulators and Signatures of Pomeranchuk-Like Behavior in Alternating Twisted Multilayer Graphene

Abstract

The moiré system constitutes a highly tunable platform for exploring exotic quantum phases, with key tuning parameters such as twist angle and displacement field (D). The breaking of specific symmetries—engineered via tailored lattice stacking—provides unprecedented control over correlated and topological phases in graphene moiré systems, an area that remains relatively underexplored. Here, we construct a moiré system with broken mirror symmetry along the z-axis—alternating twisted mono-mono-bilayer graphene (TMMBG)—and observe a pronounced asymmetry in the response to the displacement field (D). Under positive displacement fields (D > 0), correlated insulator states emerge due to a substantial reduction in the bandwidth of the moiré conduction band. Upon applying a perpendicular magnetic field, symmetry-broken Chern insulator states appear at integer fillings ν = +2 and +3. These states are absent under negative D, demonstrating that both the magnitude and sign of D govern the correlated and topological properties. Furthermore, the observation of an anomalous high-temperature resistance peak accompanied by a Hall density reset at ν = +3 reveals signatures of an entropy-driven, Pomeranchuk-like isospin crossover. These findings establish TMMBG as a powerful and novel platform for exploring the synergistic control of electronic correlations, band topology, and emergent quantum phases through the displacement field D, opening new pathways for designing advanced quantum materials with tailored many-body states.

Keywords

Alternating twisted multilayer graphene / Displacement field / Chern insulators

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The Author(s) 2026. This article is published by Higher Education Press.

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